I just readed a topic about the "Merge" command (only useable if you type it in or set up a key for it)
But I still doesn't understand what that command do, does anyone have a visual example or explain in steps how does it works ?

Hi DesuDeus, take a look at the attached 3DM file box_with_split_edge.3dm

If you select the top front edge, you'll see it is actually not just 1 edge but 2 edges there, like this:

You can use the Merge command to glue edges that are split up into fragments like that back into longer edges.

For example, select those 2 edges (or the whole box) and then run Merge by typing <tab> Merge <enter>.

Now when you go to select edges there you'll see there is just one edge there - the merge command combined the 2 edges that touched end-to-end into just 1 single edge.

For edges to be mergeable like that, they need to be only 2 edges coming off of the spot where they touch, and the edge curves need to be tangent to one another (not have a sharp corner where they touch).

Sometimes you can get split up edges like that from various things, this allows you to repair those.

In the future at some point it should also get applied to curves and surfaces as well, as a way to merge 2 curves into a single curve segment, or 2 surfaces into a single surface. That's unlike Join which glues things together but results in a segmented (for curves) or multi-surface (for surfaces) object which can be broken back into its individual parts with Separate after that.

Ok I understand now
Its just that I readed "Edges" while thinking about lines and not solids
So I thought it was the same thing than the join command

Its good to repair models indeed, so when you make a fillet to that box there's no extra edge :)

Thanks for the explanation

When you say:

In the future at some point it should also get applied to curves and surfaces as well, as a way to merge 2 curves into a single curve segment, or 2 surfaces into a single surface. That's unlike Join which glues things together but results in a segmented (for curves) or multi-surface (for surfaces) object which can be broken back into its individual parts with Separate after that.

You mean it will be possible to do a boolean union using surfaces instead of solids ?
That sounds awesome !

> You mean it will be possible to do a boolean union using
> surfaces instead of solids ?

Actually it is possible to do that already, select the 2 surfaces in the attached 3DM file and run boolean union on them.

But mostly boolean union and booleans in general are more oriented towards working with solids though, the methods that the different boolean functions use to determine which pieces to keep and which to discard is based mostly on how the different volumes interact with one another.

There is a special "plane healing" mechanism in boolean union that tries to detect when 2 planes have been glued together and tries to make a single larger plane.

Merge for surfaces would be kind of similar to that - it will take 2 untrimmed surfaces and glue them together into one single larger untrimmed surface without an edge between them unlike Join.